JPH06347013A - Combustion device - Google Patents

Abstract

PURPOSE:To keep the apparatus from enlargement in size and produce a thin gaseous mixture in a favorable mixed condition in the performance of thick and thin combustion. CONSTITUTION:Burner units 10 each consisting of a thick-combustion burner 20 combined integrally with a thin gaseous mixture-preparing unit 30 are arranged in parallel at intervals. A gaseous mixture produced by the thin gaseous mixture-preparing unit 30 is discharged from under and between the burner units 10 and mixed with air for combustion again and the thin gaseous mixture is ejected through the space between the burner units 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a so-called rich / lean combustion in which excess fuel mixture (rich mixture) and excess air mixture (light mixture) are simultaneously burned to suppress the production of nitrogen oxides (NOx). Regarding the device.

[0002]

2. Description of the Related Art Conventionally, a rich / lean combustion device has been known as one of combustion devices for achieving low NOx. This device ejects a rich air-fuel mixture with a low air ratio (the ratio of the actual air amount to the theoretical air amount) from some of the multiple flame ports and a light air-fuel mixture with a high air ratio from the other flame ports simultaneously. And burn it.

For example, as shown in FIG. 4, there has been proposed a rich / lean combustion device in which dense burners RB ejecting a rich mixture and light burners LB ejecting a lean mixture are alternately arranged in a line and burn at the same time. There is. In this case, oxygen is insufficient at the base of the flame from the rich side burner RH of the rich burner RB (hereinafter referred to as rich flame), and above the light burner LH of the lean burner LB at the top.
Oxygen becomes deficient due to the exhaust gas of the flame (hereinafter referred to as “lean flame”) from which the NOx generation is suppressed. On the other hand, in the lean flame from the lean side flame port LH, since the fuel gas is lean, the flame temperature is lowered and NOX generation is suppressed, and the synergistic effect of these causes low NOX as a whole.

[0004]

However, in order to create a light air-fuel mixture, the throat LS (introduction portion for fuel gas and combustion air) of the light burner LB must be made very large. For example, if the input of the light burner LB is the same as that of the rich burner RB and the air ratios are 2.7 (light mixture) and 0.3 (rich mixture), the desired air amount is obtained. In order to adjust the opening area of the throat LS of the light burner LB to 9 of the throat RS of the dark burner RB.
I have to double. Further, not only the throat LS but also the light burner LB itself must be enlarged. Moreover, the mixed state is deteriorated by simply increasing the size. When the mixture state of the light air-fuel mixture is poor, flashback occurs in the dark portion and combustion speed is slow in the thin portion, so that unburned gas is discharged because combustion is not completed. As described above, in the conventionally proposed combustion apparatus, it is almost impossible to actually perform the rich / lean combustion with the configuration as shown in FIG. 4, and it is impossible to increase the air ratio on the light side. Of. An object of the combustion apparatus of the present invention is to solve the above-described problems, to prevent the apparatus from becoming large due to the rich and lean combustion, and to improve the mixing of the lean air-fuel mixture.

[0005]

In the combustion apparatus of the present invention for solving the above-mentioned problems, a fuel gas and combustion air are sucked and mixed, and a rich mixture having a low air ratio is ejected from a rich flame side. A combustion device in which burners are arranged side by side with an interval, and a light-side mixture having a higher air ratio than the rich-side mixture is ejected from between the rich-side burners to form a light-side flame port next to the rich-side flame port. The light mixture flow path to the light flame side is a light mixing unit that sucks and mixes fuel gas and combustion air from its upstream side and discharges the gas mixture from a discharge port, and the discharge mixture unit. And a re-mixing unit for mixing the combustion air sent to the light side flame port direction into the mixed air to produce a high air ratio mixed air,
The light mixing unit is formed integrally with the rich side burner, and its intake port for fuel gas and combustion air is located above the intake port of the rich side burner, and the discharge port is at the bottom. The gist is that they are located.

[0006]

In the combustion apparatus of the present invention having the above-mentioned structure, the light flame side is formed next to the rich side flame hole, and the air-fuel mixture having different air ratios is ejected from each flame hole for combustion. The light air-fuel mixture ejected from the side flame mouth is created as follows. That is,
First, the fuel gas and the combustion air are mixed in the light mixing unit, and this air-fuel mixture is guided downward and discharged from the discharge port to be mixed with the combustion air in the re-mixing section to increase the air ratio and light side flame port. Send to. Therefore, the mixed state of the light air-fuel mixture becomes good by mixing twice. Further, since the air-fuel mixture is sent downward in the light mixing unit and then sent upward in the re-mixing section to be guided to the light side flame port, a sufficient mixing distance can be secured in a small space.
Further, since the light mixing unit is formed integrally with the dark side burner, it is not necessary to individually arrange the light mixing unit between the dark side burners, and the arrangement interval of the dark side burners can be narrowed. Moreover, since the suction port of the light mixing unit is located above the suction port of the rich burner, it is possible to reduce the size in the vertical direction.

[0007]

EXAMPLES In order to further clarify the constitution and operation of the present invention described above, preferred examples of the combustion apparatus of the present invention will be described below.

FIG. 1 shows a schematic structure of a combustion apparatus as one embodiment. The combustion device 1 includes a plurality of burner units 10
Are arranged in a line, and combustion air is supplied from below.

As shown in FIGS. 2 and 3, the burner unit 10 sandwiches a central partition plate 11 and has a rich burner 2 on one side.
No. 0, and the light mixing unit 30 is integrally formed on the other side. Incidentally, FIG. 2 (A) shows the dark side burner 20.
FIG. 3B is a schematic perspective view of the burner unit as seen from the formation side of the burner unit, FIG. 3B is a schematic perspective view of the burner unit as seen from the formation side of the light mixing unit, and FIG. The schematic front view of the burner unit, the same figure (B) is a schematic side view of the burner unit, and the same figure (C) is the schematic front view of the burner unit seen from the formation side of the light mixing unit.

At the lower part of one side of the burner unit 10, a throat 21 serving as an inlet for fuel gas to the rich side burner 20.
(Hereinafter, referred to as the dense side throat) is formed in the lateral direction, the fuel gas is injected and supplied from the gas nozzle 42 provided in the gas nozzle base 40, and the combustion air (primary air) is sucked accordingly. In the figure, the solid line arrow represents the flow of fuel gas, and the broken line arrow represents the flow of combustion air.
The downstream side of the thick side throat 21 is bent upward to bend the mixing chamber 2
2 (hereinafter, referred to as the dark side mixing chamber), and the rich side mixing chamber 2
2 has a plurality of flame outlets 23 (hereinafter, referred to as dark side flame outlets)
A flame mouth forming surface 24 is formed. Therefore, the fuel gas and the combustion air are mixed while passing through the rich side throat 21 and the rich side mixing chamber 22, and the mixture is rich side flame port 23.
Gushes upward from. The air ratio of this air-fuel mixture is set low, and is set to 0.5 in this embodiment. Hereinafter, this air-fuel mixture is referred to as a rich air-fuel mixture.

On the other hand, in the light mixing unit 30 provided on the back surface of the dark side burner 20, a throat 31 (hereinafter referred to as a light side throat) is formed laterally in the central portion of the burner unit 10. That is, the light side throat 31 is provided above and in parallel with the dark side throat 21. Then, the fuel gas is injected and supplied from the gas nozzle 43 to the light side throat 31, and accordingly, the combustion air is sucked. The light throat 31 downstream side is bent downward and mixed in the mixing chamber 3
2 (hereinafter referred to as the light side mixing chamber). A plurality of air-fuel mixture discharge ports 33 are formed in a line on the lower side surface of the light-side mixing chamber 32. Therefore, the fuel gas and the combustion air sucked from the light side throat 31 are sent downward (upstream side of the combustion air supplied by the blower described later) and become a mixture gas and are ejected from the discharge port 33. . That is, the light mixing unit 30 forms a flow path so that the dense burner 20 is turned upside down, and jets the air-fuel mixture laterally at the lowermost portion of the burner unit 10.

As shown in FIG. 1, the burner units 10 are arranged in parallel in the burner case 2 at a predetermined interval and are housed in the combustion chamber 3. A blower (not shown) is provided below the combustion chamber 3 and is configured to supply combustion air into the combustion chamber 3. And burner case 2
A rectifying plate 4 (for example, punching metal) is provided on the bottom surface, and the combustion air that has passed through the rectifying plate 4 flows upward between the burner units 10. Therefore, the air-fuel mixture ejected from the air-fuel mixture discharge port 33 of the light mixing unit 30 collides with the combustion air flowing between the burner units 10, is mixed, and is sent upward. In this way, a light air-fuel mixture having a high air ratio is created in this space and jetted upward from between the burner units 10. That is, the space 50 between the burner units 10 serves as the remixing section of the present invention. Hereinafter, this space 50 is referred to as a remixing unit 50. In the present embodiment, the air ratio in the light mixing unit 30 is set to the rich burner 2
It is set to 0.5 like 0, and is raised to 2.7 by mixing the combustion air in the remixing section 50. The light mixing unit 3
The air ratio at 0 may be made slightly higher than the air ratio of the rich burner 20, so that the second degree of air dilution may be made small. Of course, the air ratios of the mixing chambers 22 and 32 and the remixing unit 50 are not limited to these.

As a result, the dense flame tip 2 of each rich burner 20
At the same time as the rich air-fuel mixture erupts from the 3
A light air-fuel mixture is jetted from between the 0 flame port forming surfaces 24 (which become the light flame side 51), and is ignited by an ignition device (not shown) to perform rich / lean combustion. A band-shaped flame holding plate 52 is arranged at the light side flame port 51 to stably hold the flame.

Thus, the rich flame FR from the rich flame outlet 23
NO due to the contact between the light flame FL from the light side flame port 51 and
X can be planned. Moreover, to make a light mixture,
First, the fuel gas and the combustion air are mixed in the light mixing unit 30, this mixture is guided downward (upstream of the combustion air), and the remixing unit 50 further mixes the combustion air and guides it upward. Therefore, a sufficient mixing distance can be ensured in a small space, and the mixing state can be improved. Furthermore, since the burner units 10 in which the dark side burner 20 and the light mixing unit 30 are integrally formed are arranged at intervals, the number of parts and manufacturing man-hours are reduced, positioning is easy, and the dark side burner 20 is also provided. The interval between can be narrowed. If a separate light mixing unit is provided between the rich burners 20, not only the arrangement interval of the rich burners 20 becomes large and the apparatus becomes large, but also the combustion performance deteriorates.

Further, the dark side burner 20 and the light mixing unit 3
0 is provided on the left and right by dividing the flow path, and the dark side throat 21 is provided below the light side throat 31 so that the flow of each air-fuel mixture intersects vertically. The length can be shortened. As a result, it is possible to improve the mixing state of the light air-fuel mixture while keeping the combustion device itself compact.

In the conventional rich-lean burner, there is a concern that the temperature of the burner of the rich burner rises (because there is less combustion air) and the rich air-fuel mixture temperature rises to cause flashback. Then, the remixing section 5 around the dense burner 20
Since the light air-fuel mixture flows to 0, the rich burner 20 is cooled and there is no fear of flashback.

A fuel gas supply pipe (not shown) to the rich burner 20 and a fuel gas supply pipe (not shown) to the light mixing unit 30 are independently provided, and an electromagnetic valve for opening and closing them is provided. You may make it the structure switched according to a combustion amount. Generally, in the case of performing the dark and light combustion, the combustion becomes unstable when the capacity (combustion amount) is reduced. Therefore, when the capacity is small, the fuel supply to the light mixing unit 30 is cut off, and only the combustion air is ejected from the light side flame port 51, and Bunsen combustion with a high turndown ratio is performed for stable combustion. Of. Incidentally, in the case of such a small capacity, since the combustion amount itself is originally small, the amount of NOx generated is also small, so there is no problem. Further, instead of switching to Bunsen combustion, the number of combustion burners may be switched to adjust the capacity with the rich and lean combustion. In this case, it is desirable to prevent the slip of the light air-fuel mixture (the combustion is not completed and the raw gas is released) by making both ends a rich flame.

The embodiment of the present invention has been described above.
The present invention is not limited to these examples, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention.

[0019]

As described in detail above, according to the combustion apparatus of the present invention, it is possible to prevent the apparatus from becoming large and to improve the mixing state of the light air-fuel mixture. As a result, stable rich-lean combustion can be realized and NOX generation can be suppressed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a combustion apparatus as an example.

FIG. 2 is a schematic perspective view of a burner unit.

FIG. 3 is a front view, a side view, and a rear view of a burner unit.

FIG. 4 is a schematic perspective view of a conventional combustion device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Combustion device, 10 ... Burner unit, 20 ... Rich burner, 21 ... Rich throat, 22 ... Rich mixing chamber,
23 ... Dark side flame port, 30 ... Light mixing unit, 31 ... Light side throat, 32 ... Light side mixing chamber, 33 ... Mixture air discharge port,
50 ... Remixing part, 51 ... Light side flame mouth.

Claims (1)

[Claims] 1. A rich side burner for injecting and mixing a fuel gas and combustion air and ejecting a rich mixture having a low air ratio from a rich side flame port is arranged in parallel with a space between the rich side burners. A combustion device in which a light-side mixture having a higher air ratio than the rich mixture is ejected to form a light-side flame port next to the rich-side flame port, wherein the light-air mixture flow path to the light-side flame port is , A light mixing unit that sucks and mixes fuel gas and combustion air from its upstream side and discharges the air-fuel mixture from a discharge port, and a combustion unit that sends the discharged air-fuel mixture toward the light-side flame port And a remixing unit for mixing air to produce a light air mixture having a high air ratio, and the light air mixing unit is integrally formed with the rich burner and has an intake port for the fuel gas and combustion air. It was positioned above the suction port of the dense burner and the discharge port was positioned at the bottom. Combustion device characterized by the above.